<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        // function Array() {

        // }
        Array.prototype.mySlice = function (startIndex, endIndex) {



            var list = []
            for (var i = startIndex; i < endIndex; i++) {
                list.push(this[i])
            }
            return list;
        }
        var arr = new Array(1, 2, 3, 4, 5, 6, 7)
        console.log(arr);
        var brr = arr.mySlice(2, 4)
        console.log(brr);
    </script>
</body>

</html>